Wednesday, September 17, 2014

Identifying Bay-breasted and Blackpoll Warblers

Bay-breasted Warbler
Two of the most challenging species to separate from each other during fall migration are the Blackpoll and Bay-breasted Warblers - so much so that observed individuals are often referred to by birders as "Baypolls". In this article, Wisconsin warbler guru Tom Schultz (one of two illustrators of the Peterson Field Guide to Warblers of North America) breaks down key identification features for these confusing fall warblers. This article originally appeared on Wisconsin eBird.

The plumages of Blackpoll and Bay-breasted Warblers are indeed very similar, with both species looking substantially different than they did during the month of May. Complicating matters is the fact that the two species are also structurally very similar - with both having long primary projections, short tails, and long undertail coverts. Both species have bold whitish wingbars, white tipping on the primary flight feathers, and prominent white tail spots.

Fortunately, many individuals have markings that are quite distinctive to species - for example, once narrowed down to being a "baypoll" warbler, if a bird is observed to have any strong blush of "bay" color on the flanks, it can be safely identified as a Bay-breasted. Alternatively, if the "baypoll" can be seen to have obvious blurry dusky streaking on the upper breast and flanks, it can be safely named a Blackpoll. Also, if one can see any yellow at all on the legs, feet, or toe pads, the bird can be identified as a Blackpoll. A Bay-breasted at any age will typically have all-blackish or grayishlegs and feet - with no hint of yellow (although some may show dull pinkish on the toe pads).

The challenge, however, is with intermediate birds that may not show the distinctive markings mentioned above. In these cases, one must look carefully at a combination of several different characteristics - and hopefully a consensus can be attained that will point to one or the other species.

Read the entire article presented by eBird at: http://ebird.org/content/ebird/news/baypoll/